1. Field of the Invention
The present invention relates to a head gimbal assembly that records and reproduces various types of information into and from a recording medium using spot light formed by collecting light, and an information recording and reproducing apparatus using the head gimbal assembly.
2. Background Art
Recently, there has been a demand for further higher density of an information recording and reproducing apparatus, such as a hard disc drive in a computer device, in order to meet needs, such as to perform high-volume and high-density information recording and reproduction. To this end, recording media having a strong coercivity are now being adopted to minimize influences of one magnetic domain to an adjacent magnetic domain and vice versa and heat fluctuation. This, on the contrary, is making it difficult to record information in recording media.
In order to eliminate the inconvenience described above, there has been proposed an information recording and reproducing apparatus of a hybrid magnetic recording method configured to write information into a disc while the coercivity is lowered temporarily by heating a magnetic domain locally using spot light formed by collecting light or near-field light formed by collecting light. In particular, when near-field light is used, it becomes possible to handle optical information in a region as small as or smaller than a wavelength of light, which has been assumed to be the limit of an optical system in the related art. A higher-density recording bit exceeding that of an optical information recording and reproducing apparatus in the related art can be thus achieved.
There have been various types of information recording and reproducing apparatus of the hybrid magnetic recording method described above and one type is configured to supply light from which to generate near-field light to a near-field light element so that the near-field light element generates near-field light that is sufficiently large to achieve ultra-high resolution recording and reproduction, high-speed recording and reproduction, and a high S-to-N ratio. This information recording and reproducing apparatus allows a slider equipped with the near-field light element to scan over a recording medium and locates the slider at a desired position above the recording medium. Thereafter, by allowing near-field light emitted from the light source to cooperate with a recording field generated from the slider, information can be recorded into the recording medium.
As a light supply scheme in the hybrid magnetic recording method, there is a configuration known as a head gimbal assembly in which an optical waveguide is provided on the suspension as is described, for example, in Japanese Patent No. 4162697. There is also a configuration by which light is supplied using an optical fiber and an optical prism as is described in JP-A-2002-298302.
The head gimbal assembly in the related as described above, however, cannot supply light sufficiently. In Japanese Patent No. 4162697, as is shown in its accompanying FIG. 2, it is not anticipated to collect light exiting from the optical waveguide. It is therefore impossible to collect sufficient energy to a microscopic region comparable to 1-bit data and hence to achieve a higher-density recording bit by the hybrid magnetic recording. In order to generate a sufficiently small light spot and irradiate the light spot to a disc, it is preferable to provide a light-collecting element or a near-field light element inside the slider. In this case, however, it becomes necessary to direct light to be incident on a predetermined position of the slider. In Japanese Patent No. 4162697, because both the optical waveguide and the slider are provided on a base insulating layer (flexible substrate), it is difficult to direct light to be incident on the predetermined position of the slider.
In addition, the optical waveguide is bent at a curvature radius small enough not to interfere with an action of the suspension that controls stable levitation of the slider. It is, however, difficult for the optical waveguide to hold light within its core when bent at such a small curvature radius. As a result, there is a possibility that the information recording and reproducing apparatus fails to record information into a recording medium because the magnetic domain is not heated sufficiently during an information recording action.
Meanwhile, the configuration of JP-A-2002-298302 has no serious problem in propagation of light. However, a component, such as an optical prism, has to be fixed to the slider or the suspension. As a result, the manufacturing costs are increased and there is a concern that an increase in weight deteriorates levitation of the slider.